The largest clinical study to evaluate breast cancer screening of female survivors of childhood Hodgkin lymphoma (HL), who are at increased risk because they received chest radiation, showed that magnetic resonance imaging (MRI) detected invasive breast tumors at very early stages, when cure rates are expected to be excellent.

The finding, published in Cancer (doi:10.1002/cncr.28747), underscores the need for at-risk survivors of childhood HL and primary care physicians to be aware of established guidelines. The guidelines recommend breast MRI screening from age 25 years or 8 years following chest radiation (whichever is later), said principal investigator David Hodgson, MD, MPH, a radiation oncologist at Princess Margaret Cancer Centre, University Health Network in Toronto, Canada.

"Female survivors of childhood HL who had chest radiation should speak with their family doctor about after-care assessment and breast cancer screening" said Hodgson.

"We estimate that 75% of women who are at high risk because of prior radiotherapy to the chest are not being screened. So my hope is that this new evidence will encourage these survivors to discuss early screening with their doctors."

Hodgson's study team, in collaboration with colleagues at the Dana Farber Cancer Institute in Boston, Massachusetts, performed 274 breast MRI screens on 96 women from 2005 to 2012. Ten breast cancers—half of them invasive tumors—were diagnosed in nine women during 363 person-years of follow-up.

The median age at breast cancer diagnosis was 39 years (range 24 to 43 years), and the median latency period between HL diagnosis and breast cancer diagnosis was 21 years (range 12 to 27 years).

"This illustrates the young age at which these cancers can occur. For some of these women, if they had been screened starting at age 40 or 50, like average risk women, it would have been too late," said Hodgson.

Of the 10 detected breast tumors, five were visible on both MRI and mammography; three were visible only on MRI; and two were detected by mammography alone (but were non-invasive). The median size of invasive tumors was 8 mm (range 3-15 mm) and none had spread to the lymph nodes.

These results are substantially better than prior studies using only mammographic screening in these young patients, in which almost half of the cancers detected had cancer spread to lymph nodes.

Hodgson pointed out that because MRI screening is so much more sensitive to small changes in the appearance of the breast tissue than mammography, up to a third of patients may be called back for further testing of suspicious findings, many of which are benign or not clinically significant and therefore require no treatment. He explained that it is important to forewarn at-risk HL survivors, because call backs definitely heighten anxiety.